1. Field of the Invention
This invention relates to an AC-driving plasma display panel (PDP) of a surface-discharge type.
2. Description of the Related Art
There is growing anticipation of making fit for practical use an AC-driving PDP of a surface-discharge type as a large-scaled and thin color display unit. FIG. 4 shows a structural example of such an AC-driving PDP of the surface-discharge type. As shown in FIG. 4, plural pairs of row electrodes 12 are formed on a front glass substrate 11 constituting a display surface side so that the pairs of row electrodes 12 are set in parallel to each other and the row electrodes 12 making the pair are coated with a dielectric layer 13, which is coated with a protective layer 14 of MgO. The row electrode 12 includes a transparent electrode 12a formed of a transparent conductive film such as an ITO film or the like and a metal auxiliary electrode (a bus electrode) 12b formed of a metal film for supplementing the conductivity of the transparent electrode 12a. 
On the other hand, a plurality of column electrodes 16 are disposed in parallel to each other at given intervals on the inner surface side of a back glass substrate 15 as the back side and a phosphor layer 17 for coating each of the row electrodes 16 is also formed thereon. The front glass substrate 11 and the back glass substrate 15 are disposed separately to form closed discharge spaces 18.
Moreover, there are formed partition walls (ribs) 19 having a predetermined height and used for forming the discharge space 18 between the column electrodes 16 in each unit luminous area 22. A discharge cell is formed at each of the intersections between the pair of row electrodes 12 and the column electrode 16. Rare gas is enclosed in the discharge spaces 18.
The dielectric layer 13 is formed by applying low-melting glass paste containing, for example, lead oxide (Pbo) onto the plurality of pairs of row electrodes 12 and calcining the row electrodes 12. Furthermore, Al (aluminum), Al alloy, Ag (silver), Ag alloy or the like is used to form the metal film because the metal film is required to have low resistance in order to supplement the conductivity of the transparent conductive film.
FIG. 5 is a partial enlarged view of the pair of row electrodes as seen from the display surface side of PDP. As aforementioned, the pair of row electrodes 12 made up of the pair of transparent electrodes 12a and the pair of bus electrodes 12b which are stacked on and connected to the respective pair of the transparent electrodes 12a. The pair of transparent electrodes 12a in each unit luminous area (discharge cell) 22 have a plurality of opposing projecting portions 20 via a discharge gap 21.
The use of the transparent electrodes provided with the projecting portions as stated above allows decreasing the area of the electrode and suppressing a discharge current value. However, the front glass substrate must be precisely registered with the back glass substrate when the PDP is made in order that the discharge characteristic of each discharge cell is uniformized because the discharge characteristic of the discharge cell is adversely affected by the distance between the leading end portions of the projecting portions near the discharge gap and the partition walls. Since the registration needs accuracy in proportion as the discharge cell is reduced in size, moreover, it has been difficult to employ a transparent electrode having such a projecting portion for an extremely small discharge cell.
An object of the present invention intended to solve the foregoing problems is to provide a plasma display panel capable of demonstrating improved reliability and fine alignment.
To achieve the above object, according to a first aspect of the invention, there is provided a plasma display panel comprising:
first and second substrates disposed opposite to each other via a discharge space, said first substrate being disposed at a display side;
plural pairs of row electrodes formed on an inner surface of said first substrate and extending in parallel in a first direction with each discharge gap held therebetween;
a dielectric layer coated on said row electrodes and partially defining said discharge space;
plural pairs of column electrodes formed on an inner surface of said second substrate and extending in a second direction perpendicularly crossing the first direction and forming unit luminous areas in intersecting portions with respect to the respective pairs of first row electrodes; and
belt-like partition walls for partitioning said discharge space into said unit luminous areas in said first direction;
wherein each of said row electrodes comprises: a transparent conductive film having a body portion extending in said first direction in the proximity of said discharge gap and a projecting portion projecting in each unit luminous area from said body portion in a direction away from said discharge gap, and a metal film connected to a leading end portion of the projecting portion of said transparent conductive film and extending in said first direction.
A second aspect of the invention has been achieved by the provision of the plasma display panel according to the first aspect of the invention, wherein the surface of the dielectric layer in a portion existing on the metal film and facing the partition walls is projected toward a portion in the proximity of the discharge gap.
A third aspect of the invention is achieved by the provision of the plasma display panel according to the second aspect of the invention, wherein the surface of the dielectric layer between the adjoining metal films of the adjoining metal film of the adjoining unit luminous areas in the second direction is projected toward a portion in the proximity of the discharge gap.
In the plasma display panel according to the present invention, as the row electrode includes the transparent conductive film having the body portion extending in the first direction in the proximity of the discharge gap and the projecting portion projecting in each unit luminous area from the body portion in a direction away from the discharge gap, and the metal film connected to the leading end portion of the projecting portion of the transparent conductive film and extending in the first direction, the influence of the discharge characteristic resulting from the shifting of the relative position of the transparent conductive film to the partition wall is made reducible, whereby the registration accuracy of the front glass substrate with respect to the back glass substrate can be lessened.
In the plasma display panel according to the present invention, moreover, as the surface of the dielectric layer between the adjoining metal films adjacent to the unit luminous area in the second direction of the metal film is projected toward the portion in the proximity of the discharge gap, whereby an error discharge between the adjoining discharge cells is suppressed.